The invention relates to a switching relay, in particular for a starting apparatus for starting an internal combustion engine, having a contact device, a relay coil, an armature, an actuating rod, with the actuating rod being moved by the armature when current is supplied to the relay coil and the contact device being operated by means of the actuating rod, and having a contact breaking device by means of which the armature and the actuating rod are coupled to one another.
The invention also relates to a starting apparatus having a switching relay of this kind, and also to a mounting method and a removal method for a switching relay of this kind.
A starter motor of the starting apparatus is switched on and switched off by the switching relay. It is known in a switching relay to move the actuating rod with the armature by supplying current to the relay coil and to operate the contact device by means of the actuating rod.
Interruptions or other disturbances in the current supply when current is being supplied to the relay coil can lead to so-called fluttering contacts on the contact device, with the result that at least two contacts which adjoin one another establish a mutual connection, that is to say, as it were, stick to one another. This connection, which is created by a flow of current during fluttering, is called contact welding in the text which follows. In the case of a switching relay without a contact breaking device, the armature, on account of the lack of coupling between the armature and the actuating rod, returns to its inoperative position after the supply of current to the relay coil is switched off, but with the contact device then being operated, that is to say the contacts remaining closed, since the second spring cannot separate the contacts which are stuck to one another, that is to say cannot break the contact weld, since it does not apply a corresponding contact breaking force. Therefore, the switching function of a switching relay without a contact breaking device is disturbed after a contact welding operation. Current continues to be supplied to the starter motor or is supplied for longer, this leading to damage to the starting apparatus, to overheating, in particular to a cable fire, or to destruction of the starter motor if a vehicle battery as a power source is not disconnected in good time.
The risk is reduced with known contact breaking devices which apply a contact breaking force to the actuating rod when the relay is switched off in case a contact welding operation occurs.
DE 199 51 116 A1 describes a switching relay for a starting apparatus, with a coupling element being provided in order to carry along the actuating rod with a limited movement when the armature is moved backward only when a contact welding operation, which occurs under unfavorable conditions, occurs, and therefore the contact weld is broken by a return force of the armature.
U.S. Pat. No. 6,552,638 B2 describes a relay having a spring-assisted armature in which an actuating rod with a head is mounted. The actuating rod is moved axially by the armature against a spring force for closing a contact bridge when current is supplied. In order to break the contact bridge, in addition to the spring force, the head of the actuating rod is pulled along by a shoulder as a mating bearing into the guide in the armature in the event of a contact weld.
DE 102 60 843 A1 (D1) describes a relay, in particular a switching relay for a starter in one particular embodiment. In order to break adhesively bonded or welded contacts, a sufficient amount of kinetic energy is built up by pulsed acceleration of the magnet armature over a distance of the erosion reserve, and therefore an actuating rod is pulled back into the starting position by means of a head part when the head part runs through a distance b) in an annular groove. A relay coil is included in a housing which holds the magnet armature together in a pot-like manner.
DE 67 51 537 U (D3) describes an electromagnetic switch for starter motors of internal combustion engines. The armature has a longitudinal hole in which a bolt is secured by means of a semicircular groove in a bead in the longitudinal hole. From a mounting point of view, provision is made here to first connect the bolt to the armature in an interlocking manner, in order to then secure the bolt in the contact apparatus.
The object of the invention is to develop a switching relay of the type mentioned in the introductory part and a mounting and removal method for a switching relay of this kind in such a way that mounting and removal are simplified and the design of the switching relay is simplified.